Medical devices involving fluid flow typically involve a fluid flow path for a disinfectant operation such as a chemical disinfection. A hemodialysis device can function in place of a kidney by filtering waste, salt, and fluid from a patient's blood when the patient's kidneys do not function properly. To ensure the flow paths are properly cleaned for patient use, a chemical wash flows a disinfecting agent or other cleaning chemicals through the flow path. It is extremely critical that hemodialysis devices do not permit a chemical wash to contaminate a flow path containing fluid that may interact with a patient.
During a dialysis operation, a valve in a spent dialysate circuit is always closed, thereby preventing any potential contamination from a chemical wash. Additionally, an airgap between a water inlet valve and a hydrochamber prevents any patient contamination if there is an external loss of water pressure. During a chemical wash operation, the valve is opened so that a chemical wash or other disinfectant flows from the spent dialysate side to the hydrochamber. A drain valve opens at a periodic time interval to disinfect the drain line, and fresh water flows through the water inlet valve to replace the volume emptied out the drain valve. Under normal circumstances, the fresh water circuit is under positive pressure, so water flows into the water inlet valve, and disinfectant is prevented from flowing back through the water inlet valve.
If an external water source fails, the water is no longer under positive pressure, and the chemical wash or disinfectant has a path for potential backflow. A heat exchanger may corrode over time, resulting in an opening in a wall or membrane. In the event of an external water source pressure failure, spent dialysate, which may include a disinfecting agent if a disinfectant operation is in process, may be drawn into the water circuit from the spent dialysate circuit, potentially contaminating the external water source and fluid that may interact with a patient. Although risk to the patient is remote, a solution is needed to detect leaks in a heat exchanger and prevent all potential backflow contamination to ensure patient safety.
It is with respect to these and other considerations that the present improvements may be useful.